Sealing mat for closing reaction tubes

ABSTRACT

The invention relates to a sealing mat comprising a carrier sheet provided with a multiplicity of sealing elements for sealing test tubes. The carrier sheet, on the one hand, and the sealing elements, on the other hand, are made from different materials. The sealing elements can be made from a flexible and/or resilient material. The carrier sheet can be made from a material that is relatively stiff compared with the material of the sealing elements. The sealing elements can be detachably fixed to the carrier sheet. The sealing elements can be fixed to the carrier sheet such that they detach therefrom when the carrier sheet is pulled away while folding it over towards the rear, after sealing one or more test tubes.

The invention relates to a sealing mat for sealing test tubes, inparticular to a sealing mat comprising a carrier sheet provided with amultiplicity of sealing elements for sealing test tubes.

A sealing mat of this type is known in practice. In this known sealingmat the carrier sheet and the sealing elements are made as an integralwhole from one material and permanently joined to one another. Suchsealing mats are used in particular with storage and reagent means, suchas test tubes (also termed microtubes), microtitration plates and“Deepwell” blocks (these are test tubes permanently joined to oneanother). In this case the test tubes are in general grouped in acluster in accordance with an 8×12 matrix pattern. A major advantage ofsuch mats is that it is possible by this means as it were to open and toseal a large number of test tubes at the same time in a singleoperation. One disadvantage of the known sealing mat, amongst others, isthat opening the test tubes is not always equally easy. The sealingelements sometimes have the tendency to remain firmly seated in the testtubes, in which case a substantial force then has to be exerted on themat in order to remove the mat, under the influence of which force themat has the tendency to stretch and also to lift the tube concerned, andalso other tubes, out of the rack. Another disadvantage is that soilingor contamination can occur in other test tubes when the sealing mat isremoved. A further major disadvantage is that all test tubes have to beopened in order to gain access to one test tube. A further disadvantageis that tools must be used if an individual (single) sealing element hasto be fitted.

Within the scope of the invention a test tube is to be understood to bea container for storing substances, either in liquid form, powder form,solid form or in combinations thereof, for the purposes of chemicalanalyses, sample storage, performing chemical reactions in the testtube, etc. Such test tubes can have sizes ranging from small test tubes,such as so-called “microtubes” with a capacity of the order of 0.2 ml(or possibly less), to large test tubes having a capacity of 10 ml ormore. Within the scope of the invention a test tube must also beunderstood to be composite storage and reagent means, such asmicrotitration plates and Deepwell blocks.

U.S. Pat. No. 5,282,543 discloses a sealing mat for sealing test tubesplaced in a matrix pattern. According to a second embodiment of U.S.Pat. No. 5,282,543, the sealing mat consists of a sheet-like body thatjoins together a number of nodules which act as sealing elements and arearranged in a matrix pattern corresponding to the test tubes. Thesheet-like body is provided with passages diagonally between every twoadjacent nodules in order to guarantee adequate circulation of air forthe purposes of heat transfer from a contact block to the underside ofthe sheet-like body. The entire teaching of U.S. Pat. No. 5,282,543 isdirected towards the nodules being permanently attached to thesheet-like body.

EP-A 0 836 884 discloses a sealing system consisting of so-called innersealing means and outer sealing means. The inner sealing means consistof cylindrical components which are to be placed within the open top endof a test tube and are sealed at their tops by a flat plate-likecomponent having therein an optionally open, pre-formed passage for thepoint of a pipette. A number of inner sealing means are joined to oneanother by joining strips to give a matrix-like pattern. In this casethere is no question of a carrier sheet and EP-A 0 863 884 also does notteach that the inner sealing means can be separated from one another.For sealing, in particular, the passages in the inner sealing means EP-A0 836 884 provides outer sealing means in the form of a large sheet thatis placed over the test tubes provided with inner sealing means and ispressed down onto these to produce a seal. However, this large sheet isnot a carrier sheet for the cylindrical components of the inner sealingmeans.

The aim of the present invention is to provide an improved sealing matfor sealing test tubes.

This aim is achieved according to the invention in that the carriersheet, on the one hand, and the sealing elements, on the other hand, aremade of different materials, such as plastics. As a result of making thecarrier sheet and the sealing elements for the sealing mat of differentmaterials it becomes possible, inter alia, to use one material for thesealing elements, which, on the one hand, has very good sealingproperties, and to use a material for the carrier sheet which, on theother hand, has properties which are favourable with respect to removingthe sealing mat from the test tubes. These sealing properties on the onehand and removal properties on the other hand can then be mutuallyincompatible.

By making the carrier sheet and the sealing elements for the sealingmust of different materials it becomes possible to assign anothermaterial to one of the elements, without the characteristics of theother material being affected. Examples are different colourings ordifferent chemical resistance. However, making the carrier sheet, on theone hand, and the sealing elements, on the other hand, of differentmaterials also offers yet further advantages. Since the sealing elementshave to seal test tubes, special requirements are generally imposed onthese in connection with chemical resistance.

So that the sealing elements have a good sealing action it isadvantageous, according to the invention, if the sealing elements aremade from a flexible and/or resilient material. This makes a closefitting seal of the sealing element on the test tube possible.

According to a particularly preferred embodiment of the sealing mataccording to the invention it is highly advantageous if the sealingelements are attached to the carrier sheet such that they can beremoved. In particular, this makes it possible to be able to open,independently of one another, the test tubes sealed by means of thesealing elements. After sealing the test tubes the carrier sheet can,for example, be removed, after which each of the test tubes isindividually sealed and can also be moved individually in the sealedstate.

According to a particular further embodiment of the invention it isadvantageous if the sealing elements are attached to a carrier sheet insuch a way that they detach from the carrier sheet when the latter ispulled back, while folding it over towards the rear, after sealing oneor more test tubes. Pulling the carrier sheet back while folding it overtowards the rear, that is to say pulling it back in a directionessentially transverse to the longitudinal direction of the test tubes,prevents a force acting in the longitudinal direction being exerted onthe test tubes, which force could lift the test tubes from theircontainer or rack. The sealing mat with which sealing elements aredetachably attached to the carrier sheet has the additional advantagethat said mat can be employed more easily in an automated process.According to a further embodiment guides are therefore also provided onopposing sides of the mat.

From the production engineering standpoint the join between the sealingelements and the carrier sheet can be produced simply and reliably ifthe sealing elements are provided with a peripheral groove in which theedge of the opening made in the carrier sheet is accommodated. With thisarrangement the production procedure can be as follows:

A sheet having one opening per sealing element is first formed, forexample by punching the desired number of openings in the desiredpositions in a sheet of suitable material. This sheet is then placedtaut in an injection moulding mould, such that each opening is locatedat the position of the mould cavity for a sealing element. The edge ofthe opening in the carrier sheet will then project somewhat into themould cavity in order to be incorporated or embedded in the sealingelement on injecting the material for that sealing element. Dependingon, inter alia, the materials used for the sealing elements and thecarrier sheet, the injection moulding temperature and the duration ofthe injection moulding process, as well as on possible other factors,the sealing elements and the carrier sheet can then fuse with oneanother during this operation in order to form an integral whole or theedge of the carrier sheet can merely be accommodated in the peripheralgroove without entering into a direct join with the sealing elementother than by enclosure in the peripheral groove.

Other possible joins between the sealing elements and the carrier sheetare also conceivable, including clamping of the components on amechanical basis or gluing in some other way. Permanent and completelyloose joins can be produced by these means.

In order to make simple removal or detachment of the carrier sheetpossible by pulling the latter away by folding over towards the rear inthe case where the sealing elements have been detachably fixed to thecarrier sheet, it is advantageous according to the invention if theperipheral groove is formed just below the top end of the sealingelement. In this context “just below” is understood to be such that thesealing element is still able to overlap the carrier sheet at the top.With this arrangement the distance from the top of the groove to the topof the sealing element will in general be of the same order of magnitudeas the thickness of the carrier sheet, for example 0.25 to 4 times thethickness of said carrier sheet. It is possible, for example, to makethe distance from the top of the peripheral groove to the top of thesealing element equal to the thickness of the carrier sheet. If a 0.3 mmthick film is used for the carrier sheet this distance will then be 0.3mm, or “just below” in this example must be taken to read 0.3 mm belowthe top end. Especially in the case where the sealing elements aredetachably fixed to the carrier sheet and preferably are not fused tothe latter, this provision of the peripheral groove just below the topend of the sealing element offers the advantage that the sealing elementcan be pulled away from the carrier sheet relatively easily in thedownward direction relative to the carrier sheet. The small overlappingthickness of the sealing element, which is of the order of magnitude ofthe thickness of the carrier sheet, will then easily be able to give inorder to be able to pull the sealing element from the carrier sheet.Although not absolutely necessary, it will be clear that this“detachability” functions particularly well if the sealing elements havebeen made from a relatively flexible material, it being possible for thecarrier sheet then to have been made from a relatively rigid, oroptionally even also flexible, material.

In order to counteract the carrier sheet accidentally being able todetach from the sealing element in the downward direction over saidsealing element (if, for example, the sealing element is restrained anddownward force is exerted on the carrier sheet), it is advantageous ifthe bottom face of the peripheral groove is continued further in theoutward direction than is the top face of the peripheral groove. Thesealing element thus provides a larger support surface for the carriersheet in the downward direction, whilst said carrier sheet can still bedetached from the sealing element in the upward direction.

The sealing elements can be of solid construction, but according to theinvention it is advantageous if the sealing elements are caps, inparticular caps which are hollow on the inside and open at the top,which are suitable for accommodating in the open end of the test tubeswith an open end facing up. In this way the sealing element is moresuitable for puncturing with a needle in order to gain access to thecontents of the test tube. Because use is made of a carrier sheetcontaining holes, the needle will not have to puncture this carriersheet, which also brings various advantages.

The material to be used can be of diverse nature. The following aspectsin particular can be taken into account.

In order to counteract the contents of a test tube being able to enterinto a reaction with a sealing element it is advantageous according tothe invention if the sealing elements are made from a chemicallyresistant material.

According to the invention, sealing elements which have good closing andsealing characteristics as well as chemical resistance are obtained ifthe sealing elements are made from a TPE (thermoplastic elastomer) or PP(polypropene).

According to the invention it is particularly advantageous if thesealing elements are constructed such that they can be punctured by aneedle, preferably relatively easily.

According to the invention the carrier sheet can advantageously be madefrom a PET (polyethene terephthalate) or PP (polypropene) material.

The present invention will be explained in more detail below withreference to illustrative embodiments shown in the drawing. In thedrawing:

FIG. 1 shows a diagrammatic, perspective view of a container containingninety-six test tubes on which a sealing mat according to the inventionhas been placed;

FIG. 2 shows a diagrammatic and perspective illustration of a sealingmat according to a first embodiment of the invention;

FIG. 3 shows a diagrammatic and perspective view of an illustration of asealing mat according to a second embodiment of the invention;

FIG. 4 shows a diagrammatic sectional view of a detail of a sealing mataccording to the invention, in particular a portion of the sealing matat the location of a sealing element;

FIG. 5 shows a diagrammatic and perspective view of an illustration of asealing mat according to the invention used with a so-called “Deepwell”block; and

FIG. 6 shows a diagrammatic and perspective view of an illustration of asealing mat according to the invention used with a so-calledmicrotitration plate.

Before discussing the figures in more detail it is pointed out that whatis shown in FIGS. 1 and 4 must be seen both in relation to the firstembodiment according to FIG. 2 and in relation to the second embodimentaccording to FIG. 3. The sealing mat shown in its entirety in FIG. 1 andby means of a detail in FIG. 4 can thus, as far as what is visibleimmediately from the figures is concerned, relate both to the sealingmat according to FIG. 2 and the sealing mat according to FIG. 3. Thereason is that the difference between the embodiment according to FIG. 2and the embodiment according to FIG. 3 essentially results from thematerial used for the carrier sheet.

FIG. 1 shows a container or rack 1 in which ninety-six test tubes 2, or,more accurately, so-called “microtubes” 2, have been placed in an 8×12matrix pattern. The openings of these microtubes 2 are at the top andessentially in a flat plane. A sealing mat 3 consisting of a carriersheet 4 with ninety-six cap-shaped sealing elements 5 has been placed ontop of the microtubes 2. Each cap-shaped sealing element 5 has beenpressed as a stopper into the open top of a microtube 2 in order thatits side face 14 (FIG. 4) comes into contact with the inside wall of themicrotube to provide a closure and a seal. The sealing mat 3 is furtherprovided with a lip 6 that can serve as a grasping point for removal ofthe mat 3 or at least the carrier sheet 4.

If the carrier sheet 4 and the sealing caps 5 in the embodiment shown inFIG. 3 were to be made as an integral whole from one and the samematerial, the sealing mat 3 could then be regarded as a sealing mataccording to the prior art known in practice.

However, according to the invention in the embodiment according to FIG.3 the sealing elements 5 and the carrier sheet 4 are made from differentmaterials, which different materials will have properties which differfrom one another. Thus, “different materials” must also be understoodas, for example, two PP materials which have different compositionsand/or properties. In the case of the example shown in FIG. 3 the sheetand the sealing elements can both have been made from a PP material, butusing a PP for the sheet that differs from that used for the sealingelements.

However, an advantageous embodiment is found to be sealing elements madeof a TPE on a PP carrier mat.

As a result of using different materials for the sealing elements 5 andthe carrier sheet 4, in accordance with the invention, it becomespossible, for example, to use a material for the sealing elements 5 thathas very good properties with regard to sealing against the (inside)wall of the test tubes 2 and/or the chemical resistance and to make thecarrier sheet 4 from a material that has very good properties inparticular with regard to the removal of the sealing mat or at least thecarrier sheet and optionally also fitting of the sealing mat, which goodproperties of a material for the carrier sheet and a material for thesealing elements can be completely incompatible with one another. Thus,it becomes possible to obtain a sealing mat that in respect of, interalia, sealing, removal and fitting is appreciably better than thatdisclosed in the prior art.

With reference to FIG. 4, which is shown on a larger scale, the sealingmat 3 according to the invention can be produced by taking a carriersheet 4, for example a film having a thickness of less than 0.5 mm, asthe starting point, punching a matrix of 8×12 openings in this carriersheet 4 and then clamping this carrier sheet 4 between two mould halvesof an injection moulding in such a way that the edge portions 8 aroundthe openings 7 project into the mould cavities of the mould halves andare embedded in a groove 9, to be formed around said edge portions 8,when injection moulding the material for the sealing element 5.Enclosure of the edge portions 8 between a lower limiting surface 10 andan upper limiting surface 11 of the groove 9 is achieved in this way.Depending on the conditions during the injection moulding process and/orthe materials used for the carrier sheet 4 and the sealing elements 5and/or other conditions, fusion of carrier sheet material and sealingelement material may or may not then take place in the groove 9. If, forexample, the sealing elements are made from a TPE and the carrier sheet4 from a PP film fusion will in general then occur, whilst if thesealing elements are made from a TPE film and the carrier sheet from aPET film in general no mutual fusion but merely an enclosure or clampingwill then take place.

If fusion takes place between the carrier sheet material and the sealingelement material, the sealing elements will in general not bedetachable, or at least not easily detachable, from the carrier sheet.This embodiment is shown in FIG. 3. As is shown diagrammatically in thisfigure, the sealing elements 5 will then all be removed from the testtubes or microtubes 2 more or less at the same time, at least in oneoperation, when a pull is exerted on the lip 7.

If no fusion takes place between the carrier sheet material 4 and thesealing element material 5 or only low strength fusion takes placebetween them, the sealing elements 5 can then be detached from thecarrier sheet 4, which has the advantage that test tubes can then beleft behind which can all be handled individually in the sealed state.Such an embodiment is shown in FIG. 2, in which, after detaching aportion of the carrier sheet 4, the openings 7 in which sealing elements5 were seated are clearly visible. In the embodiment according to FIG. 2the carrier sheet can have been made from a PET and the sealing elementscan have been made from a TPE.

Again with reference to FIG. 4, it can be seen that the carrier sheet 4is accommodated a distance A just below the top 12 of the sealingelement 5 in a peripheral groove 9 that extends in the peripheraldirection about the axis 13 around the entire periphery of the sealingelement 5 and that this distance A is of the same order of magnitude asthe thickness B of the carrier sheet 4. It can also be seen that thelower limiting surface 10 of the groove 9 extends further outwards withrespect to the axis 13 than does the upper limiting surface 11 of thegroove 9. In this way a support surface for the carrier sheet 4 in thedownward direction is provided which is relatively larger than thesupport surface in the upward direction. This larger support surface 10is particularly advantageous if the sealing elements 5 are removablefrom the carrier sheet 4. Specifically, in this way it is possible tocounteract the carrier sheet 4 coming out of the groove 9 in thedownward direction as a result of pressing on the carrier sheet 4 or onan adjacent sealing element 5, which in such a case could beunintentional and could occur when pressing an adjacent or neighbouringsealing element 5, or at least to make this more difficult. The overlapwith the carrier sheet 4 is relatively small at the upper limitingsurface 11 compared with the overlap with the lower limiting surface 10,which facilitates removal of the sealing element 5 from the carriersheet 4, certainly if the sealing element 5 has been made from arelatively flexible, compliant material that is particularly verysuitable for the sealing action in a test tube. This construction makesit possible in particular, as is shown diagrammatically in FIG. 2, topull the carrier sheet 4 back and away in the manner termed “foldingover towards to the rear” in the direction of arrow C more or lessparallel to the plane in which the openings of the test tubes 2 arelocated. This pulling back and away will be easy to carry out especiallyin the case of a relatively rigid carrier sheet 4, leaving the sealingelements 5 behind in the test tubes 2.

With reference to FIG. 4 it is also pointed out that the essentiallyvertical flat portion 14 is the portion that essentially will providethe closing and seal at the inside wall of the test tube. On the groundsof, on the one hand, considerations with regard to saving of materialand, on the other hand, considerations of functionality, the sealingelements 5 are constructed as caps having an internal cavity 15 open atthe top.

The following dimensions are given merely by way of indication of thedimensions which a sealing element of a sealing mat according to theinvention could have, as far as the embodiment shown in FIG. 4 isconcerned:

Diameter D is approximately 7.5 mm Distance A is approximately 0.3 mmThickness B is approximately 0.3 mm Height H is approximately 4.8 mmOverlap E is approximately 0.3 mm.

It will be clear that these dimensions will relate to microtubes havingan opening diameter of approximately 7.5 mm. However, it will also beclear that these dimensions are merely indicative and that the sealingelements and the carrier sheet can also have other dimensions, which canbe either larger or smaller dimensions, depending on the application.

FIG. 5 shows a sealing mat according to FIG. 2 used with a “Deepwell”block, that is to say the sealing mat of the type with which the sealingelements 5 are detachable from the carrier sheet 4. This “Deepwell”block that is indicated by 20 is, as it were, a block containingintegral test tubes 21 (which thus cannot be removed from the block).However, it will be clear that the sealing mat according to FIG. 3, thatis to say the sealing mat of the type with which the sealing elements 5are permanently joined to the carrier sheet 4, can also be used with a“Deepwell” block.

FIG. 6 shows a sealing mat according to FIG. 3, that is to say thesealing mat of the type with which the sealing elements 5 arepermanently joined to the carrier sheet 4, used with a “microtitrationplate”. The microtitration plate, which is indicated by 20, is, as itwere, a plate containing integral shallow test tubes 22 (which thuscannot be removed from the plate). However, it will be clear that thesealing mat according to FIG. 2, that is to say the sealing mat of thetype with which the sealing elements 5 are detachable from the carriersheet 4, can also be used with a microtitration plate.

What is claimed is:
 1. Sealing mat comprising a carrier sheet providedwith a multiplicity of sealing elements for sealing test tubes,characterised in that the carrier sheet, on the one hand, and thesealing elements, on the other hand, are made of different materials,and wherein the sealing elements have a peripheral groove, the carriersheet has openings for receiving the sealing elements, and an edge of anopening made in the carrier sheet is accommodated in the peripheralgroove.
 2. Sealing mat according to claim 1, characterised in that thesealing elements are made from a flexible and/or resilient material. 3.Sealing mat according to claim 1, characterised in that the sealingelements are detachably fixed to the carrier sheet.
 4. Sealing mataccording to claim 1, characterised in that the sealing elements areattached to the carrier sheet in such a way that they detach from thecarrier sheet when the latter is pulled away, while folding it overtowards the rear, after sealing one or more test tubes.
 5. Sealing mataccording to claim 1, characterised in that the peripheral groove hasbeen made just below the top end of the sealing element.
 6. Sealing mataccording to claim 1, characterised in that the bottom face of theperipheral groove has been continued further in the outward directionthan has the top face of the peripheral groove.
 7. Sealing mat accordingto claim 1, characterised in that the sealing elements are caps forfitting in the open end of the test tubes.
 8. Sealing mat according toclaim 1, characterised in that the sealing elements are made of achemically resistant material.
 9. Sealing mat according to claim 1,characterised in that the sealing elements are made from a TPE(thermoplastic elastomer), in particular a TPE that can be punctured bya needle.
 10. Sealing mat according to claim 1, characterised in thatthe carrier sheet is made from a PET (polyethene terephthalate) or PP(polypropylene).
 11. Sealing mat according to claim 1, characterised inthat the sealing elements are arranged on the carrier sheet inaccordance with a matrix pattern.
 12. Sealing mat according to claim 1,wherein the matrix pattern is an 8×12 matrix pattern.
 13. Sealing mataccording to claim 1, wherein the peripheral groove is defined betweenan upper limiting surface and a lower limiting surface.
 14. Sealing matcomprising a carrier sheet provided with a multiplicity of sealingelements for sealing test tubes, characterised in that the carriersheet, on the one hand, and the sealing elements, on the other hand, aremade of different materials, wherein the sealing elements have aperipheral groove, the carrier sheet has openings for receiving thesealing elements, an edge of an opening made in the carrier sheet isaccommodated in the peripheral groove, and the sealing elements aredetachably fixed to the carrier sheet.
 15. Sealing mat according toclaim 14, characterised in that the sealing elements are made from aflexible and/or resilient material.
 16. Sealing mat according to claim14, characterised in that the sealing elements are attached to thecarrier sheet in such a way that they detach from the carrier sheet whenthe latter is pulled away, while folding it over towards the rear, aftersealing one or more test tubes.
 17. Sealing mat according to claim 14,characterised in that the peripheral groove has been made just below thetop end of the sealing element.
 18. Sealing mat according to claim 14,characterised in that the bottom face of the peripheral groove has beencontinued further in the outward direction than has the top face of theperipheral groove.
 19. Sealing mat according to claim 14, characterisedin that the sealing elements are caps for fitting in the open end of thetest tubes.
 20. Sealing mat according to claim 14, characterised in thatthe sealing elements are made of a chemically resistant material. 21.Sealing mat according to claim 14, characterised in that the sealingelements are made from a TPE (thermoplastic elastomer), in particular aTPE that can be punctured by a needle.
 22. Sealing mat according toclaim 14, characterised in that the carrier sheet is made from a PET(polyethene terephthalate) or PP (polypropylene).
 23. Sealing mataccording to claim 14, characterised in that the sealing elements arearranged on the carrier sheet in accordance with a matrix pattern. 24.Sealing mat according to claim 23, wherein the matrix pattern is an 8×12matrix pattern.
 25. Sealing mat according to claim 14, wherein theperipheral groove is defined between an upper limiting surface and alower limiting surface.